Wavelength-division-multiplexed passive optical network using wavelength-locked optical transmitter

Abstract

Disclosed is a wavelength-division-multiplexed passive optical network using a wavelength-locked optical transmitter. The wavelength-division-multiplexed passive optical network (WDM PON) includes a central office, which includes a plurality of downstream optical transmitters for outputting downstream optical signals having wavelengths according to downstream injection lights, a wavelength division multiplexer including a plurality of de-multiplexing ports linked to the plurality of the downstream optical transmitters by one-to-one, and a multiplexing port linked with the feeder fiber and performing wavelength division multiplexing and wavelength division de-multiplexing, and at least one optical switch interposed between the downstream optical transmitters and the de-multiplexing ports, inputting a downstream band light output from a selected downstream optical transmitter to the multiplexing port, and inputting a downstream optical signal output from a remaining downstream optical transmitter, which is not selected, to the de-multiplexing port.

1. A wavelength-division-multiplexed passive optical network (WDM PON) comprising:
 a central office configured to transmit a multiplexed downstream optical signal; and 
 a plurality of subscriber devices coupled to the central office via a feeder fiber, 
 wherein the central office comprises: 
 a plurality of downstream optical transmitters configured to output downstream optical signals having wavelengths according to downstream injection lights; 
 a wavelength division multiplexer including a plurality of de-multiplexing ports linked to the plurality of the downstream optical transmitters, and a multiplexing port linked to the feeder fiber, the wavelength division multiplexer configured to perform wavelength division multiplexing the downstream optical signals and wavelength division de-multiplexing a downstream band light into the downstream injection light; 
 at least one optical switch interposed between the downstream optical transmitters and the de-multiplexing ports and configured to input a downstream band light output from a selected downstream optical transmitter to the multiplexing port and for inputting a downstream optical signal output from a remaining downstream optical transmitter, which is not selected, to the de-multiplexing port; and 
 wherein the optical switch has a first port to a third port for switching the downstream optical transmitters between the de-multiplexing ports and a first optical coupler. 
 
     
     
       2. The WDM PON as claimed in  claim 1 , wherein the central office further includes a plurality of optical switches interposed between the downstream optical transmitters and the de-multiplexing ports. 
     
     
       3. The WDM PON as claimed in  claim 2 , wherein the central office further includes a controller configured to select an idle downstream optical transmitter from among the plurality of downstream optical transmitters and for controlling the optical switch coupled to the selected downstream optical transmitter. 
     
     
       4. The WDM PON as claimed in  claim 1 , wherein the central office includes a downstream broadband light source, which inputs a different downstream band light to the first optical coupler. 
     
     
       5. The WDM PON as claimed in  claim 1 , wherein the central office includes a second optical coupler, which inputs coupled downstream band lights input from the first optical coupler to the multiplexing port and transmits a multiplexed downstream optical signal output from the multiplexing port through the feeder fiber. 
     
     
       6. The WDM PON as claimed in  claim 1 , wherein the downstream optical transmitter is a Fabry-Perot laser diode. 
     
     
       7. The WDM PON as claimed in  claim 1 , wherein the downstream optical transmitter is a reflective semiconductor optical amplifier. 
     
     
       8. The WDM PON as claimed in  claim 1 , wherein the central office further comprising a plurality of optical filters coupled between the plurality of optical switches and the de-multiplexing ports. 
     
     
       9. The WDM PON as claimed in  claim 8 , wherein the central office further comprising a plurality of upstream optical receivers coupled to the plurality of optical filters.